Date of Award
12-2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Environmental Engineering and Earth Science
Committee Chair/Advisor
Michael Carbajales-Dale
Committee Member
Timothy DeVol
Committee Member
Brandon Ross
Committee Member
Weichiang Pang
Abstract
Mass timber has emerged as a leading candidate for low-carbon construction, offering the dual benefits of reduced embodied emissions and biogenic carbon storage. Yet, fully realizing its sustainability potential requires a comprehensive and context-specific understanding of its environmental performance across the entire life cycle, from raw material production to building operation and beyond end-of-life (EoL). This dissertation advances life cycle assessment (LCA) practices for mass timber by addressing critical challenges across multiple phases of its life cycle. This dissertation is comprised of three published papers, and two submitted manuscripts. First, I conducted a critical review and meta-analysis of mass timber production (cross laminated timber and glued laminated timber), revealing significant regional variability in carbon emissions and energy demand, with non-European production showing markedly higher impacts. This highlights that timber products cannot be treated as globally uniform commodities in environmental assessments. Second, I carried out the first harmonization of mass timber construction LCAs, reducing methodological inconsistencies and demonstrating systematic differences between modeled and constructed buildings, thereby improving comparability and reliability of results. Third, building on these foundations, I developed and assessed the environmental performance of a novel all-wood long-span floor system designed for carbon negativity, adaptability, and disassembly. A cradle-to-gate LCA showed that designs using only mechanical fasteners consistently outperformed adhesive-based designs across most impact categories, emphasizing the importance of connection choice. Fourth, I evaluated circular EOL strategies for novel floor systems, modeling recovery pathways including landfilling, downcycling, component reuse, and full assembly reuse across multiple recovery rates. Results identified break-even thresholds for downcycling (59%) and confirmed modular reuse as the most effective strategy for achieving net-negative emissions. This work advances the field by explicitly linking recovery efficiency to climate outcomes and quantifying the benefits beyond building life (Stage D). Finally, this work was further extended to a comparative whole-building LCA, which evaluated the implication of the novel wood floor system in a mass-timber office building against a conventional steel–concrete structure in the U.S. Southeast. While the timber design comprised of the novel wood floor system demonstrated material efficiency, reduced global warming potential, and increased renewable energy use, the analysis revealed that EoL assumptions critically shape net climate benefits. Collectively, this research provides a more holistic understanding of the environmental sustainability of mass timber. By integrating systematic reviews, harmonization, structural innovation, and forward-looking circularity analysis, it delivers actionable insights for designers, policymakers, and industry stakeholders seeking to operationalize life cycle thinking and accelerate the transition to low-carbon, circular construction.
Recommended Citation
Ijeoma, Muzan Williams, "Advancing Life Cycle Assessment of Mass Timber: Environmental Performance, Circular Design and End-Of-Life Strategies" (2025). All Dissertations. 4162.
https://open.clemson.edu/all_dissertations/4162
Author ORCID Identifier
https://orcid.org/0009-0004-6400-1405